This invention generally relates to devices and methods for visualization of elongated devices for therapeutic or diagnostic procedures in a patient's body. In particular, the invention relates to the positioning of the distal end of a catheter or catheter system within a patient's body using radiopaque marker members in conjunction with fluoroscopic or other suitable visualization systems. One specific application of the invention includes visualization of the distal end of an elongated delivery catheter while performing myocardial revascularization, tissue ablation, delivery of an angiogenic agent, or other desired therapy.
Myocardial revascularization typically involves tissue ablation, tissue injury, or formation of one or more channels in a patient's heart wall which defines the heart chamber, particularly the left ventricle. The first trials of the revascularization process were made by Mirhoseini et al. Lasers in General Surgery (Williams & Wilkins; 1989), pp. 216-223. Other early disclosures of this procedure are found in an article by Okada et al. in Kobe J. Med. Sci 32, 151-161, October 1986 and in U.S. Pat. No. 4,658,817 (Hardy). Both of these references describe intraoperative revascularization procedures which require the chest wall to be opened and which include formation of the revascularization channels completely through the heart wall, i.e., the epicardium, myocardium and endocardium.
Copending application Ser. No. 08/561,526 filed on Nov. 21, 1995 (Aita et al.), which is incorporated herein in its entirety, describes an intravascular system for myocardial revascularization which is introduced percutaneously into a peripheral artery and advanced through the patient's arterial system into the left ventricle of the patient's heart. The revascularization channels are not usually formed through the entire heart wall but only the endocardium and into the myocardium from within the left ventricle. This procedure eliminates the need of the prior intraoperative procedures to open the chest cavity and to penetrate through the entire heart wall in order to form the channel. While the percutaneous methods and systems for introducing revascularization devices developed by Aita et al. represent a substantial advance, one of the difficulties in revascularizing a patient's left ventricle by means of a percutaneously introduced revascularization system has been accurately visualizing the location of the distal tip of the tissue ablaton or injury device to a desired region of the patient's endocardium and maintaining the placement of the distal end of the device against a desired region of the ventricular wall at a proper angle, i.e., perpendicular or nearly perpendicular to the endocardium, while the heart is beating. The anatomy of human hearts and particularly the relationship of the ascending aorta and the left ventricle can vary considerably from patient to patient. The entry angle from the ascending aorta through the aortic valve into the left ventricle of a human heart does not facilitate the easy access to the free wall of the patient's heart which in substantial part defines the left ventricle.
Prior methods have involved the use of a delivery catheter made from polymeric tubing with a radiopaque material impregnated within the polymer wall, or a symmetric band of radiopaque metal attached to the distal end of the delivery catheter. However, with these devices and methods it can be difficult to determine the precise axial and rotational orientation of the distal end of the delivery catheter due to the symmetries of the marking system when viewed under two dimensional fluoroscopy. This can be cured in part by rotating the fluoroscopy unit to a second viewing angle and visualizing the distal end of the catheter from the second angle. The second viewing angle will sometimes provide enough information for the operating physician to determine the precise orientation of the distal end of the catheter, however, this process is cumbersome and time consuming. Another option is to use a bi-planar fluoroscopic unit to take views from two different perspectives, however, this process is also cumbersome, and the equipment required to do so is expensive.
What has been needed is an improved system and method for visualizing a delivery catheter or delivery catheter system during a percutaneous procedure. In particular, what has been needed is a system and method for fluoroscopic visualization of a catheter that facilitates visualization under two dimensional fluoroscopy without the need to view from more than one plane. The present invention satisfies these and other needs.